Abstract
This study was conducted to evaluate the effects of Clostridium butyricum dietary supplementation on the growth, antioxidant, immune response, gut microbiota, and intestinal barrier function of broilers under high stocking density (HSD) stress. A total of 324 1-day-old Arbor Acres male broilers were randomly assigned to three treatments with six replicates, each replicate including 18 chickens (18 birds/m2). The experiment lasted 6 weeks. The three treatments were basal diet (control, CON), basal diet supplemented with 1 × 109 colony forming units (cfu)/kg C. butyricum (CB), and basal diet supplemented with 10 mg/kg virginiamycin (antibiotic, ANT). The results showed that the body weight (BW) and average daily gain (ADG) of broilers in the CB group were significantly higher than those in the CON group in three periods (p < 0.05). The total antioxidant capacity (T-AOC) and the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity in serum of the CB group were significantly increased compared with those in the CON and ANT groups at 42 days (p < 0.05). At 42 days, the serum immunoglobulin M (IgM) and immunoglobulin G (IgG) levels of the CB group were significantly higher than those of the CON group. Compared with the CON group, interleukin-1β (IL-1β) in the CB group was significantly decreased in the starter and grower stages (p < 0.05), but there was no significant difference between the two treatment groups (p > 0.05). C. butyricum significantly decreased the high stocking density-induced expression levels of IL-1β and tumor necrosis factor-α (TNF-α) in the ileum of broilers at different stages. Additionally, C. butyricum could increase the expressions of claudin-1 and zonula occludens-1 (ZO-1) in intestinal tissue. Moreover, C. butyricum significantly increased the Sobs and Shannon indices in the CB group compared with the ANT group (p < 0.05), while the Ace index in the CB group was significantly higher than that of the CON group (p < 0.05). Furthermore, by using 16S rRNA gene sequencing, the proportion of Bacteroides in the CB group was increased compared to those in the CON and ANT groups at the genus level. In conclusion, C. butyricum supplemented into feed could improve the growth performance and feed utilization of broilers by promoting immune and intestinal barrier function and benefiting the cecal microflora.
Highlights
During the past decade, the poultry industry in China has been developing rapidly, especially under the impact of African swine fever, when the pork production had been struck largely and the price was beyond the reach of ordinary people
Broilers fed diets supplemented with C. butyricum had higher body weight (BW) and average daily gain (ADG) and lower feed conversion ratio (FCR) compared with those in the CON group, and no differences were found in the growth and feed utilization between the CB group and the antibiotic treatment (ANT) group
Similar results have been reported in Svejstil et al (2019), which showed that a C. butyricum CBM 588-supplemented diet positively affected the growth and feed conversion of broiler chickens
Summary
The poultry industry in China has been developing rapidly, especially under the impact of African swine fever, when the pork production had been struck largely and the price was beyond the reach of ordinary people. In 2020, the annual sales volume of broilers in China was nearly 9.34 billion, which increased by 4.5% compared with that in 2019, indicating that people’s demand for chicken is increasing (Xin et al, 2021) To meet such high demand, the poultry industry has turned the breeding mode into a high-density, intensive, and rapid one to improve the feeding efficiency and reduce the cost (Hong et al, 2012) in order to achieve a satisfactory economic return. Such feeding conditions may induce chronic stress, which leads to birds being more susceptible to infectious diseases, causing related physiological and immunological stress (Li W. et al, 2019) and impairing their health, deceasing their production efficiency. The use of probiotic bacteria can improve the immune function, inhibit pathogenic microorganisms, modulate the intestinal barrier function, optimize the intestinal flora structure, etc. (Liu X. et al, 2019; Peng et al, 2019; Zhan et al, 2019; Zhao et al, 2020)
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